The L1A1 rifle overcame initial prejudice against it and by the mid-1960s the British Army was justifiably proud of its rifle. However, despite the original redesign, it was still considered to be too heavy, expensive and complex. In the late 1960s, a major modernization program was carried out to produce the L1A2 version. Compared to the L1A1, the L1A2 featured detail improvements and enhancements that optimized the rifle for mass production; some parts and assemblies were conceived using simplified manufacturing methods. Notably, the L1A1's milled steel receiver was replaced by a U-shaped steel stamping. As a result of these modifications, the L1A2’s weight was reduced by approx. 1 kg (2.2 lb), the accuracy during automatic fire was increased and several reliability issues were addressed. The L1A1's chrome-lined barrel was retained, a common feature of Soviet weapons which resists corrosion that would otherwise result from the corrosive-primed ammunition and sporadic cleaning practices.
The L1A2’s receiver, compared to the L1A1, has a stamped sheet metal housing to which a rear stock trunnion and forward barrel trunnion are fastened using rivets. The receiver housing also features a rigid tubular cross-section support that adds structural strength. Guide rails that assist the bolt carrier’s movement which also incorporates the ejector are installed inside the receiver through spot welding. The forward barrel trunnion has a non-threaded socket for the barrel and a transverse hole for a pin that secures the barrel in place. On some models the rear trunnion has two extended mounting arms on both sides that support the buttstock; other fixed models use a stepped shaped trunnion that covers the full width of the inside of the receiver. As a weight-saving measure, the stamped dust cover is of thinner gauge metal than that of the L1A1. In order to maintain strength and durability it employs both longitudinal and latitudinal reinforcing ribs.
The L1A2’s barrel is installed in the forward trunnion and pinned (as opposed to the L1A1, which has a one piece receiver with integral trunnions and a barrel that is screwed-in). Additionally the barrel has horizontal guide slots that help align and secure the handguards in place. To increase the weapon’s accuracy during automatic fire, the L1A2 was fitted with a slotted muzzle brake that helps redirect expanding propellant gases upward and to the right during firing, which mitigates the rise of the muzzle during an automatic burst when held by a right-handed firer. The muzzle brake is threaded on to the end of the barrel with a left-hand thread. The gas block in the L1A2 does not have a cleaning rod capture or sling loop but is instead fitted with an integrated bayonet support collar that has a cleaning rod guide hole. The forward sling loop was relocated to the front handguard retainer cap. The handguard retainer also has notches that determine the position of the handguards on the barrel. Gas relief ports that alleviate gas pressure in the piston cylinder. The L1A2’s bolt carrier is slightly lighter in weight and hase some minor differences in its shape. The L1A2 uses a modified return spring mechanism, which replaces the single recoil spring guide rod with a dual “U”-shaped wire guide.
The L1A2 quickly replaced the L1A1 in service and by the mid-1970s all British units were equipped with the rifle.